Field of the Invention
The present invention relates to the use of a material for producing hydrogen or electricity, wherein the material is based on magnesium.
In one particular application, the hydrogen is converted into electricity in a fuel cell and the electricity so produced is used to power an electric motor, for example a bicycle booster motor.
Description of Related Art
Hydrogen production is one of the main challengers to replace fossil fuels and move towards the production of “green” and sustainable energy. In fact, gaseous dihydrogen, which we will call “hydrogen” in the present application, represents a very good alternative fuel because it offers high power density, while the products of its combustion or its use in a fuel cell are non-polluting. In particular, the combustion of hydrogen does not generate CO2 (carbon dioxide).
In recent decades, much effort has been devoted to the production of hydrogen in large quantities. In this context, catalytic reforming of fossil fuels remains the method of choice today. However, electrolysis and plant fermentation are also considered as alternative possibilities.
The production of hydrogen on the basis of the hydrolysis reaction of various materials is another avenue of investigation. This method has the advantage that no additional energy is required (low temperature operation), while the method makes it possible to produce hydrogen in a delocalised manner and at a purity that is suitable for many applications.
Many types of materials have already been considered, including complex hydrides, metals, metal hydrides and intermetallics. Of these materials, magnesium has attracted attention for hydrogen production by hydrolysis due to its high electrochemical activity, low density and low cost. In addition, it is a non-toxic and abundant product. Magnesium and magnesium hydride react with water according to the following respective equations:Mg+2H2O=Mg(OH)2+H2  (Eq.1)MgH2+2H2O=Mg(OH)2+2H2  (Eq.2)
These reactions have a theoretical yield of hydrogen production, by weight and without taking water into account, of respectively 8.2% and 15.2%. However, these reactions are always more or less blocked by the formation of an Mg(OH)2 hydroxide layer, which limits their interest in practice.
An object of the invention is therefore to provide a material whose use allows producing hydrogen by hydrolysis, or electricity from this hydrogen, and offers improved conversion efficiency.